Determination of chromium(III) and chromium(VI) by use of a spectrophotometric sequential injection system

Mulaudzi, Ludwig Vusimuzi; Staden, Jacobus Frederick van; Stefan, Raluca‐Ioana

doi:10.1016/s0003-2670(02)00188-5

Cited by 37 publications

(14 citation statements)

References 25 publications

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“…One of the most used colorimetric methods for the Cr(VI) andyor total chromium determination is based on the reaction of Cr(VI) with diphenylcarbazide (DPC) (Lynch et al, 1984;Andrade et al, 1985;Milacic et al, 1992;Sule et al, 1996;Clesceri et al, 2002;Mulaudzi et al, 2002;Giusti et al, 2005). The absorbance of the red -violet complex of unknown composition, formed at the pH range of 1.6 -2.2, is read at 540 nm (Clesceri et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

“…The sample acidification carried out before the DPC addition prevents the solubilization of Cr(III) species, the releasing of Cr(III) from complexes or colloidal particles, or even the increase of Cr(VI) reduction by organic compounds in the sample (Sule et al, 1996). Studies showed that interferences from organically complexed Cr(III) species were almost negligible in soil extracts when non-acidified DPC was used, and more significant with acidified DPC (Milacic et al, 1992 (Clesceri et al, 1998), as well as the removal of organic compounds from the samples (Mulaudzi et al, 2002), have been proposed. Very few methods for Cr determination are based on the formation of Cr(III) complexes in aqueous solution, and this is probably due to the slow reaction rate of the strongly hydrated Cr(III) ions.…”

Section: Introductionmentioning

confidence: 99%

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Simultaneous speciation of chromium by spectrophotometry and multicomponent analysis

Soares

Carneiroa

Monteiro

et al. 2009

Chemical Speciation & Bioavailability

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A simple, fast and sensitive spectrophotometric method for the simultaneous determination of Cr(III) and Cr(VI) in effluents and contaminated waters using a UV-visible spectrophotometer, which operates with an advanced software for multicomponent analysis, is proposed. The method consists in the complexation of Cr (III) with EDTA and reaction of Cr(VI) with diphenylcarbazide (DPC). Variables, such as pH and colour stability time, were studied. The effect of concomitant ions on the simultaneous Cr(III) and Cr(VI) determination was also investigated. The sums of the chromium species concentrations obtained by the proposed method were compared with the total chromium concentrations found by electrothermal atomic absorption spectrometry. Recoveries of the chromium species between 75 and 136% were obtained for spiked samples. The linear working range for Cr(III) was 0.5 -30 mg L

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simultaneous speciation of chromium by spectrophotometry and multicomponent analysis

Soares

Carneiroa

Monteiro

et al. 2009

Chemical Speciation & Bioavailability

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“…For example, chromium speciation is of great interest from an environmental point of view, owing to the different toxicities of Cr(VI) and Cr(III) species. Chromium is widely distributed in nature, i.e., in rocks, plants, animals, soil, water and volcanic dust and gases, 28 and is heavily used in industry. 29 It is well known that Cr(III) is a trace element essential for the proper functioning of living organisms and is indispensable in the metabolism procedure of glucose and lipid mammals.…”

Section: Introductionmentioning

confidence: 99%

Automation of Liquid–Liquid Extraction–Spectrophotometry Using Prolonged Pseudo-Liquid Drops and Handheld CCD for Speciation of Cr(VI) and Cr(III) in Water Samples

et al. 2005

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A simple spectrophotometric system, based on a prolonged pseudo-liquid drop device as an optical cell and a handheld charge coupled device (CCD) as a detector, was constructed for automatic liquid-liquid extraction and spectrophotometric speciation of trace Cr(VI) and Cr(III) in water samples. A tungsten halogen lamp was used as the light source, and a laboratory-constructed T-tube with two open ends was used to form the prolonged pseudo-liquid drop inside the tube. In the medium of perchloric acid solution, Cr(VI) reacted with 1,5-diphenylcarbazide (DPC); the formed complex was automatically extracted into n-pentanol, with a preconcentration ratio of about 5. The organic phase with extracted chromium complex was then pumped through the optical cell for absorbance measurement at 548 nm. Under optimal conditions, the calibration curve was linear in the range of 7.5 -350 µg L -1 , with a correlation coefficient of 0.9993. The limit of detection (3σ) was 7.5 µg L -1 . That Cr(III) species cannot react with DPC, but can be oxidized to Cr(VI) prior to determination, is the basis of the speciation analysis. The proposed speciation analysis was sensitive, yet simple, laboreffective, and cost-effective. It has been preliminarily applied for the speciation of Cr(VI) and Cr(III) in spiked river and tap water samples. It can also be used for other automatic liquid-liquid extraction-spectrophotometric determinations.

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“…Many studies, which employed the process of oxidizing Cr (III) by using an oxidant in the FIA and SIA system, conformed that the quantitative data could be obtained under constant analytical conditions. 10,16,18 Calibration curves between 0.1 and 50 µg/L by three replication injection of 5 mL to investigate the determination of Cr (III) and Cr (VI) under the optimum conditions of the proposed FIA system were plotted (Figure 8 Comparison of both species showed 2% of difference between both of gradients, while around 3.6% of difference between concentrations obtained by two regression equations in a virtual value of peak area,…”

Section: Respectivelymentioning

confidence: 99%

Spectrophotometric Determination of Ultra trace Tri & Hexavalent Chromium by Using on-line Flow Injection Analysis with Dual Pre-concentration Column

Jung¹,

Lim²,

Kang³

et al. 2011

Bulletin of the Korean Chemical Society

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An on-line flow injection analysis with dual pre-concentration method was developed to determine the ultra trace tri and hexavalent chromium in water. In this system, the cation and anion pre-concentration columns were combined with a 10-port injection valve and then used to separate and concentrate Cr (III) and Cr (VI) selectively. The two species of concentrated chromium were sequentially eluted and determined by using HClKCl buffer of pH 1.8 as an eluent. Cr (III) was oxidized by hydrogen peroxide to Cr (VI). It was detected spectrophotometrically at 548 nm by complexation with DPC (diphenylcarbazide). Several factors such as concentration of H 2 O 2 , DPC and coil length in reaction condition were optimized. The linear range for Cr (III) and Cr (VI) was 0.1-50 µg/L. The limit of detections (3σ) of Cr (III) and Cr (VI) were 52 ng/L and 44 ng/L under the optimized FIA system, and their recoveries 98% and 103%, respectively. This method was applied to analyze contamination level of chromium species in tap water, groundwater and bottled water.

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Determination of chromium(III) and chromium(VI) by use of a spectrophotometric sequential injection system

Cited by 37 publications

References 25 publications

Simultaneous speciation of chromium by spectrophotometry and multicomponent analysis

Simultaneous speciation of chromium by spectrophotometry and multicomponent analysis

Automation of Liquid–Liquid Extraction–Spectrophotometry Using Prolonged Pseudo-Liquid Drops and Handheld CCD for Speciation of Cr(VI) and Cr(III) in Water Samples

Spectrophotometric Determination of Ultra trace Tri & Hexavalent Chromium by Using on-line Flow Injection Analysis with Dual Pre-concentration Column

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